This invention relates to an apparatus for centering and feeding a log and to a method for centering and feeding a log, which are adapted to be used in combination with a working machine for turning a log while chucking the log by means of cutting spindles.
There is known a veneer lathe provided with cutting spindles having, in the direction of Z thereof, an axial center for chucking a log to be cut or peeled into a monolithic veneer (hereinafter referred simply to as a veneer). There is also known an apparatus for centering and feeding a log (or a log centering and feeding apparatus), which is designed to feed a log to the cutting spindles of the veneer lathe in such a manner that the log can be properly centered.
FIG. 23 shows part of one example of the conventional log centering and feeding apparatus which is disclosed in Japanese Patent Unexamined Publication H4-60001, wherein one side portion of the log-chucking section of the apparatus is illustrated. According to this log centering and feeding apparatus, a pair of centering spindles 100 (only one of them is shown) having an axial center in the same Z direction as that of the cutting spindles (not shown) of the veneer lathe are disposed away from the cutting spindles by a predetermined distance in the direction of X. The centering spindles 100 are mounted on a guiding shaft 103 which is horizontally interposed between a pair of frames 101 erected vertically (in the direction of Y), and the position of centering spindles 100 is made adjustable by means of an X-axis adjustor comprising a fluid cylinder (not shown), etc. A pair of transporting claws 104 (only one of them is shown) are disposed over the centering spindles 100 in such a manner that the position of each of the transporting claws 104 can be adjusted in the vertical direction (in the direction of Y) by means of a Y-axis adjustor comprising a fluid cylinder 105, etc. and the transporting claws 104 are made entirely movable along the rail 110 or in the direction of X toward the cutting spindles of the veneer lathe.
Further, a plurality of log center detecting means each provided with a displacement detector 121 for detecting the position of center of a log (not shown) while the log is being kept chucked by the centering spindle 100 is mounted on a proximal end of each rocking arm 120 which is positioned at a desired interval along the longitudinal direction (in the direction of Z) of the log. In this case, the centering spindle 100 holding the log is rotated at least one revolution thereby enabling each log center detecting means to determine, through processing, each position of axial center which is assumed to constitute the axial centers at both end faces of the log, thus obtaining coordinate values on the axial center throughout the full length of log, on the basis of which the pair of centering spindles 100 are respectively shifted along the horizontal guiding shaft 103 by making use of the X-axis adjustor thereby performing the positional correction in the direction of X. Thereafter, each of the transporting claws 104 is moved downward to a predetermined degree so as to allow the log (that has been determined regarding the positional correction in the direction of X) to be held using the transporting claws 104, after which the log is moved in the vertical direction (in the direction of Y) up to a predetermined position by making use of the Y-axis adjustor (comprising the fluid cylinder 105), thereby performing the positional correction in the direction of Y. After finishing the alignment of axial center of log in both X and Y directions, the transporting claws 104 is moved, while maintaining this state of log. in the direction of X toward the cutting spindle of the veneer lathe so as to transfer the log to the cutting spindle.
As described above, according to the conventional log centering device, the adjustment data is output to the X-axis adjustor as well as to the Y-axis adjustor on the basis of data of axial center of log which have been obtained through the processing of data obtained from the displacement detector and from the rotation angle detector, whereby the log is shifted in the directions of X-axis and Y-axis so as to make the axial center of the log agree or align with the cutting spindle, thus performing the centering of the log.
However, since the aforementioned conventional centering device requires not only the X-axis adjustor for moving the holding claw (centering spindle 100) in the direction of X-axis but also the Y-axis adjustor for moving the transporting claw 104 in the direction of Y-axis, the log centering device itself inevitably becomes large in size and at the same time, becomes complicated in structure, thus inviting an increase in cost.